The present disclosure relates to accelerated testing methods and systems of silicone drainage in medical devices, and in particular, syringes used in a medication delivery device.
Syringes are used to deliver medication. Syringes include a barrel extending between a flange and a shoulder that leads to a needle hub. The medication may be contained within the barrel and dispensed by movement of a piston slidable along the inner walls of the barrel. When stored, the syringes have the needle end facing up and the flange end pointing down. Silicone or other substances are disposed along the inner walls of the syringe for lubrication and extended sealing. After syringes have been siliconized, the syringes may be stored for significant periods of time. During this storage time, the initial distribution of silicone may change as the silicone drains from the top to the bottom (that is, from the needle end toward the flange end) under gravity. Understanding these changes due to silicone drainage is necessary to appreciate the effects of changes in silicone distribution of empty syringes during storage on injection functionality and in silicone particulate levels in prefilled syringes once filled with medication. Currently, only empirical methods are available for these types of assessments and the methods require studies with extended durations to document the effects of empty component storage and filled syringe storage over time. These studies can require substantial duration. As an example, it can take over 6 years to study the combined effects of the maximum allowed empty and filled storage times for the syringes, if up to four years for the storage of empty syringe barrels before filling is desired and up to two years for the storage of filled syringes is desired after the maximum empty storage has elapsed. Accordingly, there is a need to understand the silicone drainage from a first principles perspective and to use this understanding to identify a way to accelerate the studies so that useful information can be created in a much shorter time than 6 years and/or overcome one or more of these and other shortcomings of the prior art.